Support - Accuracy

What is calibration and why is it important?
Calibration is the process of determining the numerical relationship
between the observed sensor output (i.e. ADC output voltage) and the
known value of pressure being applied to the particular sensor. The
Stepscan® Tile is considered calibrated if its pressure measurements are
within a predetermined range of the known applied pressure. The system
must be carefully calibrated to obtain the best results in terms of
accuracy and repeatability for the end user. The accuracy and
repeatability of measurements obtained on a PMD will vary among levels
of applied pressure, calibration procedure, duration of pressure
application, frequency of pressure application (i.e. static or dynamic),
contact surface compliance/elasticity, contact surface shape (i.e. flat
or curved), previous loading history, etc. calibration should be
performed under conditions that are as close as possible to the actual
measurement conditions.

Does the system come calibrated?
Yes, each of the 14,400 sensors of the Stepscan® Tile Unit is
individually calibrated across the entire pressure range before being
delivered to the end user.

How accurate is the Stepscan® device?
Accuracy; Hysteresis ≥95%

Does it need to be calibrated and how often?
Each of the 14,400 sensors of a Stepscan® Tile Unit are individually
calibrated across the entire pressure range in-factory before being
delivered to the customer. It is recommended that the system be
calibrated at least once a year. The customer can check the calibration
accuracy on site using our COP (Center of Pressure) device available
with the sale of the Stepscan® system.

Can I calibrate the tile? How will they know if the calibration is correct?
The end user cannot calibrate the tile. To ensure the highest
standard of accuracy the tile is in-factory calibrated after
manufacturing. The customer can verify if the calibration is correct
using a COP (Center of Pressure) device and do on-site periodic
assessment of the accuracy of COP, as well as local load and mean
pressure under the COP feet. If the calibration is not optimized, the
tile must be returned to Stepscan’s head office for in-factory
recalibration.

What control parameters are in place to ensure the quality of the performance of the Stepscan® Tiles?
On a select number of Tiles we have developed Standard Operating Procedures to test for the following technical parameters.

Pressure Distribution

Hysteresis

Creep

COP

Cross-Talk

Accuracy after fatigue

Bandwidth

The results of these tests are compared with i-FAB standards to assess
the floor tiles functionality. The equipment used to perform these
tests is the same as that is used to calibrate the tiles.

How does the instrument scan/the
sensors scan? Is the scanning a snapshot with all 14,400 firing
simultaneously or are the sensors sequentially scanning?
Each tile is composed of four quarter tiles, with 60 rows of 60
sensors each (3600 sensors total). For each image, the quarter tile
scans through its sensors, one row of 60 sensors at a time, but very
rapidly (<100us per row). Each of the quarter tiles perform this
process independently and send the data to a central processor in the
tile, which combines them and forwards the full-tile data to the
Stepscan® Software application. This application combines and
synchronizes data from multiple tiles to give multi-tile images, where
the sensor data is collected within the same time slice (e.g., 10ms for
100Hz sampling rate).

StepScan®

Stepscan Technologies Inc. is a Canadian technology company located on the East coast in the Province of Prince Edward Island. Its primary product, the Stepscan Gait Analysis flooring system, is medical grade equipment that is currently marketed and sold in Canada, the US, Australia, Mexico and China.